Antibacterial personal care compositions are known in the art. Especially useful are antibacterial cleansing compositions, which typically are used to cleanse the skin and to destroy bacteria and other microorganisms present on the skin, especially the hands, arms, and face of the user.
Another class of antibacterial personal care compositions is the hand sanitizer gels. This class of compositions is used primarily by medical personnel to disinfect the hands and fingers. The hand sanitizer gel is applied to, and rubbed into, the hands and fingers, and the composition is allowed to evaporate from the skin. Wiping of the composition from the skin is not necessary because the high alcohol content of present-day hand sanitizer gels leads to a fast and essentially complete evaporation of the composition from the skin.
Antibacterial compositions in general are used, for example, in the health care industry, food service industry, meat processing industry, and in the private sector by individual consumers. The widespread use of antibacterial compositions indicates the importance consumers place on controlling bacteria and other microorganism populations on skin. It is important, however, that antibacterial compositions provide a substantial and broad spectrum reduction in microorganism populations quickly and without problems associated with toxicity and skin irritation.
In particular, antibacterial cleansing compositions typically contain an active anti- bacterial agent, a surfactant, and various other ingredients, for example, dyes, fragrances, pH adjusters, thickeners, skin conditioners, and the like, in an aqueous and/or alcoholic carrier. Several different classes of antibacterial agents have been used in antibacterial cleansing compositions. Examples of antibacterial agents include a bisguanidine (e.g., chlorhexidine digluconate), di-phenyl compounds, benzyl alcohols, trihalocarbanilides, quaternary ammonium compounds, ethoxylated phenols, and phenolic compounds, such as halo-substituted phenolic compounds, like PCMX (i.e., p- chloro-m-xylenol) and triclosan (i.e., 2,4,4'-tri-chloro-2'hydroxydiphenylether). Present-day anti-microbial compositions based on such antibacterial agents exhibit a wide range of antibacterial activity, ranging from low to high, depending on the microorganism to be controlled and the particular antibacterial composition.
Hand sanitizer gels contain a high percentage of an alcohol, like ethanol. At the high percent of alcohol present in the gel, the alcohol itself acts as a disinfectant. In addition, the alcohol quickly evaporates to obviate wiping or rinsing skin treated with the sanitizer gel. Hand sanitizer gels containing a high percentage of an alcohol, i.e., about 40% or greater by weight of the composition, however, have a tendency to dry and irritate the skin.
Most commercial antibacterial compositions generally offer a low to moderate antibacterial activity. Antibacterial activity is assessed against a broad spectrum of microorganisms, including both Gram positive and Gram negative microorganisms. The log reduction, or alternatively the percent reduction, in bacterial populations provided by the antibacterial composition correlates to antibacterial activity. A log reduction of 3-5 is most preferred, a 1-3 log reduction is preferred, whereas a log reduction of less than 1 is least preferred, for a particular contact time, generally ranging from 15 seconds to 5 minutes. Thus, a highly preferred antibacterial composition exhibits a 3-5 log reduction against a broad spectrum of microorganisms in a short contact time.
It should be noted that high log reductions have been achieved at pH values of 4 and 9, but such log reductions are attributed at least in part to these relatively extreme pH values. Compositions having such extreme pH values can irritate the skin and other surfaces, and, therefore, typically are avoided, especially as hand sanitizer compositions which typically are not wiped or rinsed from the skin after use. It has been difficult to impossible to achieve a high log reduction using an antibacterial composition having a neutral pH of about 5 to about 8, and especially about 6 to about 8, without simultaneously incorporating a high percentage of an alcohol.
For example, WO 98/01110 discloses compositions comprising triclosan, surfactants, solvents, chelating agents, thickeners, buffering agents, and water. WO 98/01110 is directed to reducing skin irritation by employing a reduced amount of surfactant.
Fendler et al. U.S. Pat. No. 5,635,462 discloses compositions comprising PCMX and selected surfactants. The compositions disclosed therein are de- void of anionic surfactants and nonionic surfactants.
WO 97/46218 and WO 96/06152 disclose compositions based on triclosan, organic acids or salts, hydrotropes, and hydric solvents.
EP 0 505 935 discloses compositions con- taining PCMX in combination with nonionic and anionic surfactants, particularly nonionic block copolymer surfactants.
WO 95/32705 discloses a mild surfactant combination that can be combined with antibacterial compounds, like triclosan.
WO 95/09605 discloses antibacterial compositions containing anionic surfactants and alkylpolyglycoside surfactants.
WO 98/55096 discloses antimicrobial wipes having a porous sheet impregnated with an antibacterial composition containing an active anti-microbial agent, an anionic surfactant, an acid, and water, wherein the composition has a pH of about 3.0 to about 6.0.
N. A. Allawala et al., J. Amer. Pharm. Assoc.--Sci. Ed., Vol. XLII, no. 5, pp. 267-275, (1953) discloses the antibacterial activity of active antibacterial agents in combination with surfactants.
A. G. Mitchell, J. Pharm. Pharmacol., Vol. 16, pp. 533-537, (1964) discloses compositions containing PCMX and a nonionic surfactant that exhibit antibacterial activity. The compositions disclosed in the Mitchell publication exhibit antibacterial activity in at least 47 minutes contact time, thus the compositions are not highly effective.
With respect to hand sanitizer gels, Osborne et al. U.S. Pat. No. 5,776,430 discloses a topical antimicrobial cleaner containing chlorhexidine and an alcohol. The compositions contain about 50% to 60%, by weight, denatured alcohol and about 0.65 to 0.85%, by weight, chlorhexidine. The composition is applied to the skin, scrubbed into the skin, then rinsed from the skin.
European Patent Application 0 604 848 discloses a gel-type hand disinfectant containing an antimicrobial agent, 40% to 90% by weight of an alcohol, and a polymer and a thickening agent in a combined weight of not more than 3% by weight. The gel is rubbed into the hands and allowed to evaporate to provide disinfected hands. As illustrated in EP 0 604 848, the amount and identity of the antibacterial agent is not considered important because the hand sanitizer gels contain a high percentage of an alcohol to provide antibacterial activity. The disclosed compositions often do not provide immediate sanitization and do not provide residual antibacterial efficacy.
In general, hand sanitizer gels typically contain: (a) at least 60% by weight ethanol or a combination of lower alcohols, such as ethanol and isopropanol, (b) water, (c) a gelling polymer, such as a crosslinked polyacrylate material, and (d) other ingredients, such as skin conditioners, fragrances, and the like. Hand sanitizer gels are used by consumers to effectively sanitize the hands, without, or after, washing with soap and water, by rubbing the hand sanitizer gel on the surface of the hands. Current commercial hand sanitizer gels rely on high levels of alcohol for disinfection and evaporation, and thus suffer from disadvantages. Specifically, current hand sanitizer gels have a tendency to dry and irritate the skin because of the high levels of alcohol employed in the compositions.
Also, because of the volatility of ethyl alcohol, the primary active disinfectant does not remain on the skin after use, thus failing to provide a persistent, or residual, antibacterial effect.
At alcohol concentrations below 60%, ethyl alcohol is not recognized as an antiseptic. Thus, in compositions containing less than 60% alcohol, an additional antibacterial compound must be present to provide antibacterial activity. Prior disclosures, however, have not addressed the issue of which composition ingredient in such an antibacterial composition provides bacterial control. Therefore, for formulations containing a reduced alcohol concentration, the selection of an antibacterial agent that provides both a rapid antibacterial effect and a persistent antibacterial benefit is difficult. Prior compositions also have not provided an effective, fast, and broad spectrum control of bacteria at a neutral pH of about 5 to about 8, and especially at about 6 to about 8.
An efficacious antibacterial composition has been difficult to achieve because of the properties of the antibacterial agents. For example, several active antibacterial agents, like phenols, have an exceedingly low solubility in water, e.g., triclosan solubility in water is about 5 to 10 ppm (parts per million). The solubility of the antibacterial agent is increased by adding alcohols to the composition. However, an increase in solubility of the antimicrobial agent, and in turn, the amount of antibacterial agent in the composition, does not necessarily lead to an increased antibacterial efficacy.
Accordingly, a need exists for an antibacterial composition, particularly a hand sanitizer composition, that is highly efficacious against a broad spectrum of Gram positive and Gram negative bacteria in a short time period, and that provides residual antibacterial activity, wherein the antibacterial activity is attributed primarily, or solely, to the presence of the active antibacterial agent in the composition. The present invention is directed to such antibacterial compositions.